Process of treating cellulosic films



Patented Feb. 10, 1925. V

UNITED STATES PATENT OFFECE.

HENRY E. VAN DERHOEF AND JACKSON B. WELLS, OF ROCHESTER, NEW YORK, AS-SIGNORS TO EASTMAN KODAK COMPANY, OF ROCHESTER, NEW YORK, A CORPORA-TIGN OF NEW YORK.

PROCESS OF TBLsLATING CELLJLOSIC FILMS.

No Drawing. Application filed January 12, 1924. Serial/fie. 685,906.

To all'whomz't may concern: After the photographic films new passed Beitknown that We, HENRY 111. V AN UER- through the photographic baths andbeen 55 new and J AOKSON l5, \VELLS, citizens of the dried, s curlingtendency manifests itself. United States of America residing at Roch-Where the roar face'oi' the support free or ester, in the county ofMonroe and Stet u1 :'overc(l,lhis tendency may reach an mole-- of NewYork, have invented certain new one. sir-able degree. Of course, filmswhich are useful Improvements in Processes of Treutcoated on the hookwith. a layer, such as gel 60 ing Cellulosio Films, of which thefollowing mine, have very little curling propen. t b t is a full, clear,and exact specification. in certain types of films, for instance motionThis application. is a. continuation in part picture films, u gclotinelnwl-ring not in of our application, Serial No. 592,846, filed generaluse, her-misc it interferes illi the Oct. 6, 1922, for Process ofremoving dye drying of the films on the conventionalreeks. 65 fromtinted celluiosic film. Whiio the curiiu tendency in motion pic- Thisinvention relates to a process of treat tore n'lni, purt cinorly themost widely used ing cellulosic films, which is capable ofrcnitrocellulose ones, may not manifest itself moving dye l'roln tintedor colored lilins and to u lmrn'ii'ul extent in u greet runny cases, islikewise capable of lessening the curling nevertheless, when the lihn issubjected, as tendency of cellulosic filins. Une object of it sometimesis, to especially severe condithe invention is to provide a relativelyinoxtions, the curling becomes bothersome. It is, pensive and easilycontrolled process for therefore, desirable to provide a way for Whollyor partially removing dye from tintlessening the curling tendencywithout iined eellulosic films and for lessening the curl pairing thefilm support or s.i.=lr-stsnt -.lll (lising tendency of cellulosicfihns. Another ohsolving it 5 ject is to provide a process of thischaracter We have discovered a process which solves 25 in which thenecessary steps do not impair hoth the dye-removal probl m} the curlorsubstantially dissolve the film. Other ohlessening problem. In otherwords, the stop. jects will hereinafter appear. constituting our processhave the iulwm-ui Our invention is especially applicable to property ofeither removin g dye or lo ers the treatment of cellulosie bases orsupports mg curling, or doing both oil? thes things siso forphotographic lilm. It will, therefore, he inultoncously, according towhether the film described in connection with such film by to he treatedcontains rig- (r not. way of example. in i'ni'rying out our process welilafii. the so As is well known to those skilled in the support,pmi'rrnhl only the rear one there art, the cellulosic buses or supportsfor phowith ii solvent of ihc rcilui hm re #5 tographic film aresubstantially impermeable out of -which the has iminml T to water and tophotographic aqueous solo to 11'; is so restrietml that there tions,such as fixiiu baths and the like. For many :1 temporarisoftening and,z-emso some purposes, such, for instance, as the protinting action on hesuppor but the utter duction 01' motion picture positive films, the notsuhstentially dissolved, and after dry 40 cellulosie support isfrequently dved,-thut ing preserves practically its former appearis, itat least lnclurles a colored or (iyed layer. mice. The restriction ofthe solvent action, 7 The latter is usually, but not necessarily, on sothat it does not impair the support, may the rear side of the support,such side being he cfi'ecml by controlling the time (luring defined asthat which is opposite 'to the [are which the solvent. contacts with thefilm, by 45 which bears the light-sensitive or photo-- stlvciillgsolvents having the desired degree graphic emulsion. Sometimes during;the of solvontpowcr, by regulating; the amount 7 process of manufacturethis colored layer of s-zilve-nl applied. per unit area of filo? loobecomes too deep in tint. It is then Jlift$- s, by mixing u solvent witha non Snrv to reduce the color without suhslunsolve .t, etc. The lustmined expedient has tialiy dissolving or in any Way impairing the beenfound to be especially practicable, and base or support. Furthermorethis rcduo we. shall, therefore, describe it by way of tion in colormust be under sullicient oontroi, illustration. so that it can bestopped at the desired. point. The cellulosio material most commonlyemployed for film supports is nitrocellulose mixed, of course, with theusual modifying substances. The p roxylin base thus em ployed, whendyed, has coloring matter mixed throughout the base or in a layerincorporated with the latter. Usualy a relatively thin nitrocelluloselayer bearing the coloring material forms the rear part or face of thebase.

If the tint or color is found to be too deep in this rear layer, thefilm or support may be brought into contact with a bath composed of asolvent such as acetone, preferably toned down with a non-solvent, suchas water, say for instance parts of the former to 30 parts of the latterby weight. While the whole su port prior to coating with thephotograplrieally sensitive layer might be simply immersed in the bath,we prefer, however, to merely bring the rear face of it in contact withthe treating bath. Differently stated, the same result is effected ifthe bath be applied to the rear face of the support. Rollers, wicks,jets, or any other well known expedicnts in the art may be employed toefiect this application of the liquid. The action of the bath is .undervery accurate control by regulating the time that the film contacts witha bath of given temperature and strength. Room tenr eratures areordinarily sufiicient and preferred, although, a slight heating ispermissible if considered desirable for accelerutin the action. Theaction is also facilitated if the li uid is kept in motion while itcontacts with the rear face. Any of the well known machines in this artmay be used for this purpose. While the rear face of the sup port may betreated after the photographic coating as been applied to it,nevertheless, we refer to act upon the substantially cure sup ort orbase before it is made up into the 'shed photographic film. Acetone is asolvent of dyes commonly used. If the film had any original tendency tocurl, this treatment greatly lessens it, so that it withstandssubsequent photographio treatment without buckling and kinking to aharmful degree. If the film does not have the dyed layer, but thetreatment, as described above, is nevertheless applied to its rear face,the curling tendency will be simlarly lessened regardless of the absenceof e.

ere dye is to be entirely removed from colored film scrap or old coloredfilm, the material is moved through the bath without the convolutions ofthe film touching each other, or it may be chopped into small pieces andthe latter acted upon by the mixture. Preferably the bath is a itated inany event. The liquid, when wor ing on a large scale, can convenientlyflow counter to the movement of the film base being treated. Anadvantage of our process in connection which has a so with scrap is thefact that the dye is thor oughly and rapidly leached out withoutdissolving the film, the latter being in condition for the well knownrecovering proccsses. If the scrap were dissolved, the dye would be allthe more thoroughly mixed in the nitrocellulose.

Of course, many equivalent baths which include solvents or mixtures ofsolvents and non-solvents may be employed. Moreover, if the solventshave a solvent action with respect to the lilleis or softeners in thesup port, no harm is done. The acetone, given in the above example, hasa solvent tendency with respect to many of the common softeners innitrocellulose films and yet it is successful in the above describedexample. Anothcrw instance of useful baths is methyl alcohol mixed withbutyl alcohol or water, a convenient bath being 85 parts of methylalcohol to 15 parts of butyl alcohol by weight. It will be noted thatthe baths given by we o'f example are substantially free from mineralmatter and substances of such high boiling point that they would remainon the rear face of the film in quantities suificient to impair thelatter.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent is:

l. The process of treating nitrocellulose film support having a freerear face, which comprises actin on said rear face with a nitroceliuioscso vent substantially free from non-volatile substances until saidsolvent penetrates throu h said rear face, and stopping said actionefore the body of the film support is acted on.

2. The process of treating nitrocellulose film sup ort havin a rear facesubstantially uniform y accc'ssib e to solvents, which comprisestemporarily softening the material of said support at said rear face byapplying to "said face a volatile solvent thereof, substantially freefrom non-volatile ingredients, stopping the action of said solventbefore nitrocellulose is substantially dissolved away thereby, andevaporating applied solvent from said face. i

3. The process of treating cellulose film support having dye therein adacent the rear free face thereof, which comprises acting on said facewith a liquid which has a solvent effect on said dye and sufiicientsolvent tendenc toward said film to penetrate the latter, an limitingthe'action of said liquid to avoid substantial dissolving away of saidcellulosic film.

4. The process of simultaneously removing dye and lessening thecurling-tendency of nitrocellulose film support'which has dye thereinadjacent its free rear face, which comprises acting on said face with a.liquid vent effect on said dye and suflicient solvent tendency towardsaid nitrocellulose to penetrate to the dye, and stop; tially dissolvingthe film during the removal ping the action of said liquid efore itsubof the dye.

stantially dissolves away nitrocellulose from said support.

5; The process of removing dye from dyed cellulosic films impermeable towater, which includes the step of treating a face of said film with aliquid which has a solvent action on said dye and a temporary softeningaction onsaid oellulosic films Without dissolving the latter durin theremoval of the dye, said face being afi accessible to said liquid.

6. The process of removing dye from dyed cellulosic film impermeable towater which includes the step of treating said film with 'a'liquidcontaining a substance which is a solvent of said film and a substancewhich is a non-solvent of said film,'at least one of said substancesbein a solvent of said dye, the proportion of lm solvent beingsuflicient to temporarily soften the film for penetration of said dyesolvent without substan- 7. The processof removing dye from dyedcellulosic film impermeable to water, which includes the step oftreating said film with a solvent of said film mixed with water, themixture being a solvent of said dye, and the proportion of film-solventbeing insufficient to dissolve the 'film during the removal of the dye,but sufficient to temporarily penetrate said film.

8. The process of removing dye from a dyed nitrocellulose filmimpermeable to Water, which includes the step of treating said film witha mixture of 70 parts of acetone and parts of water until the desireddegree of removal is reached.

igned at Rochester, New York, this 31st day of December, 1923.

HENRY E. VAN DERHOEF. JACKSON B. WELLS.

cellulose to penetrate to the d e, and stop ping the action of saidliquid efore it substantially dissolves away nitrocellulose from saidsupport.

5; The process of removing dye from dyed cellulosic films impermeable towater, which includes the step of treating a face of said Y film with aliquld which has a solvent action cient to temporarily soften the filmfor ponetration of said dye solvent without substantially dissolving thefilm during the removal of the dye.

7. The process of removing dye from dyed cellulosic film impermeable toWater, which includes the step of treating said film with a solvent ofsaid film mixed with Water, the mixture being a solvent of said dye, andthe proportion of film-solvent being insufficient to dissolve the filmduring the removal of the dye, but suflicient to temporarily penetratesaid film.

8. The process of removing dye from a dyed nitrocellulose filmimpermeable to water, which includes the step of treating said film witha mixture of 70 parts of acetone and parts of water until the desireddegree of removal is reached.

Signed at Rochester, New York, this 31st day of December, 1923.

HENRY E. VAN DERHOEF. JACKSON B. WELLS.

Certificate of Correction.

It is hereb certified that in Letters Patent No. 1,525,761, grantedFebruary 10, 1925, upon t e a plication of Hen'ry E. Van Derhoef andJackson B. Tells. of

Rochester, New

'ork, for an improvement in Processes of Ircating (.ellulosic films, anerror appears in the printed. spevii icnt ion requiring correct ionfollows: age 2, line 1125, claim 3, for the word cellulose readcellulosio; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 31st day of March, A. D. 1925.

KARL FENNING, Acting Commissioner of Patents.

Certificate of Correction.

It is hereb certified that in Lebter Patent No. 1,525,761, rantedFebruary 10, 1925, upon 1; e a plication of Hen'ry E. Van Derhoef andackson B. \Vells, of iochester, New ork, for an improvement in Processesof Treating Cellulosic {ilmsf an error appears in the print/illspecification requiring cormctiun as follows: age 2, line 1115, claim 3,for the \YQlTl cellulose read miluinsic; and that the said LettersPatent should be reaxl with this correct-ion therein that the same mayconform to the record of the case in the Patent Office.

Signed and sealed this 31st day of March, A. D. 1925.

'[smu] KARL FENNING,

Acting; Commissioner of Patents.

